Abstract: There are many inventions described herein as well as many aspects and embodiments of those inventions, for example, circuitry and techniques for reading, writing and/or operating a semiconductor memory cells of a memory cell array, including electrically floating body transistors in which an electrical charge is stored in the body of the transistor. In one aspect, the present inventions are directed to one or more independently controllable parameters of a memory operation (for example, restore, write, refresh), to program or write a data state into a memory cell. In one embodiment, the parameter is the amount of time of programming or writing a predetermined data state into a memory cell. In another embodiment, the controllable parameter is the amplitude of the voltage of the control signals applied to the gate, drain region and/or source region during programming or writing a predetermined data state into a memory cell. Indeed, the controllable parameters may be both temporal and voltage amplitude.

Abstract: A semiconductor storage device including a memory cell. In the memory cell a buried electrode is formed on a semiconductor substrate. A semiconductor layer is formed on the buried electrode via a buried insulating film. A surface electrode is formed on the semiconductor layer via an insulating film. A source region and drain region are formed in the semiconductor layer on both sides of the surface electrode with a predetermined spacing therebetween. A floating body is formed between the source region and drain region, which stores data in accordance with whether holes are stored in the floating body. The buried electrode serves as a gate electrode, and the surface electrode serves as a plate electrode.

Abstract: In an improved EASB programming scheme for a flash device (e.g. a NAND flash device), the number of word lines separating a selected word line (to which a program voltage is applied) and an isolation word line (to which an isolation voltage is applied) is adjusted as a function (e.g. inverse function) of distance of the selected word line from the drain side select gate to reduce program disturb due to high vertical and lateral electric fields at or near the isolation transistor when programming word lines closer to the drain side select gate. The selected and isolation word lines are preferably separated by two or more word lines to which intermediate voltage(s) are applied.

Abstract: A semiconductor integrated circuit device is provided on a semiconductor substrate, and includes a plurality of word lines, a plurality of data lines, and a plurality of electrically programmable and erasable non-volatile memory cells respectively coupled to the plurality of word lines and to the plurality of data lines. The erasable non-volatile memory cell each includes a MIS transistor having a floating gate having a first level polycrystalline silicon layer, a source, and a drain coupled to the corresponding data line, and a control gate formed of a semiconductor region in the semiconductor substrate, the control gate being coupled to the corresponding word line.

Abstract: A memory cell having a programmable solid state electrolyte layer, a writing line and a controllable switch that is arranged between the solid state electrolyte layer and the writing line. The controllable switch has a control input that is connected with a selecting line and the switch also has a limiting element that limits a current through the solid state electrolyte layer to a predetermined amount of electric charge for a write operation.

Abstract: A storage transistor is programmed as a non-volatile memory element by biasing the source and drain while a programming voltage is applied to the gate. The substrate is held at a different potential than the source/drain to insure that the greatest difference in voltage during the programming step occurs between the channel region and the gate, rather than the gate and the source/drain. The programming voltage heats the channel region to form a non-volatile low-resistance connection between the source and drain, which is read to determine the programmed state.

Abstract: A semiconductor device comprises an N-type insulated-gate field-effect transistor including a first insulating layer that is provided along side walls of a gate electrode, has a negative thermal expansion coefficient, and applies a tensile stress to a channel region of the N-type insulated-gate field-effect transistor. The device also comprises a P-type insulated-gate field-effect transistor including a second insulating layer that is provided along side walls of a gate electrode, has a positive thermal expansion coefficient, and applies a compression stress to a channel region of the P-type insulated-gate field-effect transistor.

Abstract: A semiconductor memory device is disclosed, which includes a first SRAM cell which includes cross-connected first and second inverters having first and second nodes, a first transistor connected between a first bit line and the first node and having a gate connected to a first write word line, a second transistor connected between a second bit line and the second node and having a gate connected to the first write word line, a third transistor having a gate connected to the second node, a fourth transistor connected between the first bit line and the third transistor and having a gate connected to a read word line, and a second SRAM cell which includes fifth-eighth transistors corresponding to the first-fourth transistors and has substantially the same configuration as the first SRAM, wherein the drains of the fourth and eighth transistors are connected to the first and second bit lines, respectively.

Abstract: An integrated DRAM-NVRAM, multi-level memory cell is comprised of a vertical DRAM device with a shared vertical gate floating plate device. The floating plate device provides enhanced charge storage for the DRAM part of the cell through the shared floating body in a pillar between the two functions. The memory cell is formed in a substrate with trenches that form pillars. A vertical wordline/gate on one side of a pillar is used to control the DRAM part of the cell. A vertical trapping layer on the other side of the pillar stores one or more charges as part of the floating plate device and to enhance the DRAM function through the floating body between the DRAM and floating plate device. A vertical NVRAM wordline/control gate is formed alongside the trapping layer and is shared with an adjacent floating plate device.

Abstract: A non-volatile memory is provided. A substrate having a number of trenches and a number of select gates is provided. The trenches are arranged in parallel and extend in a first direction. Each of the select gates is disposed on the substrate between two adjacent trenches respectively. A number of select gate dielectric layers are disposed between the select gates and the substrate. A number of composite layers are disposed over the surface of the trenches and each composite layer has a charge trapping layer. A number of word lines are arranged in parallel in a second direction, wherein each of the word lines fills the trenches between adjacent select gates and is disposed over the composite layers.

Abstract: A semiconductor integrated circuit includes non-volatile memory elements (PM1, PM2), each of which has a first source electrode, a first drain electrode, a floating gate electrode and a control gate electrode and is capable of having different threshold voltages, and read transistor elements (DM1, DM2), each of which has a second source electrode and a second drain electrode and is capable of having different mutual conductances according to the threshold voltage of the non-volatile memory element. The read transistor element has a switching state according to the electron injection state or the electron emission state, in other words, the writing state or the erasing state of the floating gate electrode. In a read operation, it is not necessary to cause a channel current to flow according to the threshold voltage of the non-volatile memory element.

Abstract: An electronic device can include a substrate including a first trench having a first bottom and a first wall. The electrode device can also include a first gate electrode within the first trench and adjacent to the first wall and overlying the first bottom of the first trench, and a second gate electrode within the first trench and adjacent to the first gate electrode and overlying the first bottom of the first trench. The electronic device can further include discontinuous storage elements including a first set of discontinuous storage elements, wherein the first set of the discontinuous storage elements lies between (i) the first gate electrode or the second gate electrode and (ii) the first bottom of the first trench. Processes of forming and using the electronic device are also described.

Abstract: A write and erase method of a semiconductor memory device includes a floating gate type transistor having a semiconductor substrate, a gate insulating film formed on the semiconductor substrate, a floating gate electrode formed on the gate insulating film, and a control gate electrode opposing the floating gate electrode with a hollow portion being sandwiched therebetween. A capacitance between the semiconductor substrate and the control gate electrode is controlled by one of an operation of forming, in the hollow portion, an electrical path which electrically connects the floating gate electrode and the control gate electrode, and an operation of eliminating the electrical path.

Abstract: An integrated DRAM-NVRAM, multi-level memory cell is comprised of a vertical DRAM device with a shared vertical gate floating plate device. The floating plate device provides enhanced charge storage for the DRAM part of the cell through the shared floating body in a pillar between the two functions. The memory cell is formed in a substrate with trenches that form pillars. A vertical wordline/gate on one side of a pillar is used to control the DRAM part of the cell. A vertical trapping layer on the other side of the pillar stores one or more charges as part of the floating plate device and to enhance the DRAM function through the floating body between the DRAM and floating plate device. A vertical NVRAM wordline/control gate is formed alongside the trapping layer and is shared with an adjacent floating plate device.

Abstract: A non-volatile semiconductor memory device comprising a plurality of non-volatile semiconductor memory cells, an interface making data exchange with an external device to write/read data with respect to the non-volatile semiconductor memory cells, and a control circuit for controlling the non-volatile semiconductor memory cells, wherein the interface and the control circuit include a first read mode initialized via a first bootstrap to read data from the non-volatile semiconductor memory cells for continuously outputting (N+M)-byte (N is the n-th power of 2, n is positive integers) data via the interface, and a second read mode initialized via a second bootstrap to read data from the non-volatile semiconductor memory cells for continuously outputting K-byte (K is the k-th power of 2, k is positive integers) data via the interface.

Abstract: A memory cell is programmed by injecting charge into a charge storage layer of the memory cell. A desired programmed charge results in the charge storage layer over an edge portion of a channel region of the memory cell. An undesired programmed charge results in the charge storage layer over an inner portion of the channel region. Charge tunneling is used to substantially remove the undesired programmed charge in the charge storage layer. In one form the memory cell has a substrate having a channel region, a first dielectric layer over the substrate and a charge storage layer over the first dielectric layer. A second dielectric layer over the charge storage layer has a first portion that is thicker than a second portion to selectively control the charge tunneling.

Abstract: A memory cell unit including: a semiconductor substrate having a source diffusion layer in at least a part of a surface thereof; a column-shaped semiconductor layer provided on the semiconductor substrate, and having a drain diffusion layer provided in an uppermost portion thereof and a first low concentration impurity diffusion layer provided in an entire bottom portion thereof; a memory cell arrangement which includes a plurality of memory cells provided in a peripheral wall of the column-shaped semiconductor layer and connected in series perpendicularly to the substrate, the memory cells each having a charge storage layer and a control gate; a second impurity diffusion layer provided at a lower end of the memory cell arrangement; and a selection transistor having a gate electrode provided around the peripheral wall of the column-shaped semiconductor layer and connecting the second impurity diffusion layer and the first impurity diffusion layer; wherein the first impurity diffusion layer extends into a part

Abstract: A semiconductor storage apparatus including cell arrays, each having a plurality of memory cells connected to a pair of first and second bit lines; and sense amplifiers, each being provided corresponding to the pair of first and second bit lines and sensing data read out from the memory cell to be read out, wherein each of the sense amplifiers includes a current mirror circuit having first and second current paths connected directly or indirectly to the pair of first and second bit lines; and the current mirror circuit includes: a first transistor which has a source and a drain short-circuited to each other and flows a reference current between the source and the drain; and a second transistor, of which gate is commonly connected to a gate of the first transistor, and which flows a current passing through the memory cell to be read out between a source and a drain thereof.

Abstract: A plurality of nonvolatile memory cells that constitute a nonvolatile memory are disposed in array form. Selection MIS•FETs for memory cell selection are electrically connected every bits. Each of the nonvolatile memory cells has a MIS•FET for writing data, a MIS•FET for reading data, and a capacitance section. Gate electrodes of the MIS•FETs and a capacitance electrode of the capacitance section are constituted of part of the same floating gate electrode. A control gate electrode of the nonvolatile memory cell is formed of part of an n well to which the capacitance electrode is opposite.

Abstract: A non-volatile memory system including an array of cells, each having an access transistor and a capacitor sharing a floating gate. The access transistors in each row are fabricated in separate well regions, which are independently biased. Within each row, the source of each access transistor is coupled to a corresponding virtual ground line, and each capacitor structure is coupled to a corresponding word line. Alternately, the source of each access transistor in a column is coupled to a corresponding virtual ground line. Within each column, the drain of each access transistor is coupled to a corresponding bit line. Select memory cells in each row are programmed by band-to-band tunneling. Bit line biasing prevents programming of non-selected cells of the row. Programming is prevented in non-selected rows by controlling the well region voltages of these rows. Sector erase operations are implemented by Fowler-Nordheim tunneling.

Abstract: A non-volatile memory device comprises a plurality of bit lines extending in a first direction, a plurality of word lines extending in a second direction substantially perpendicular to the first direction, a plurality of memory cells provided respectively so as to correspond to the positions of the intersections between the plurality of bit lines and the plurality of word lines, a plurality of source lines corresponding to a plurality of memory cells which are connected to a same bit line, a current source capable of supplying the constant current to a selected memory cell and the corresponding bit line and a voltage control circuit which keeps a voltage of a selected bit line equal to or higher than a predetermined voltage.

Abstract: A flash memory device can include a semiconductor pin protruding from a semiconductor substrate of a first conductive type to extend in one direction, a first doped layer and a second doped layer provided to an upper portion and a lower portion of the semiconductor pin, respectively, to be vertically spaced apart from each other, the first and second doped layers having a second conductive type, and a plurality of word lines extending over a top and a sidewall of the semiconductor pin to intersect the direction. The word lines overlap the first doped layer and the second doped layer to have vertical channels.

Abstract: A non-volatile memory system including an array of cells, each having an access transistor and a capacitor sharing a floating gate. The access transistors in each row are fabricated in separate well regions, which are independently biased. Within each row, the source of each access transistor is coupled to a corresponding virtual ground line, and each capacitor structure is coupled to a corresponding word line. Alternately, the source of each access transistor in a column is coupled to a corresponding virtual ground line. Within each column, the drain of each access transistor is coupled to a corresponding bit line. Select memory cells in each row are programmed by band-to-band tunneling. Bit line biasing prevents programming of non-selected cells of the row. Programming is prevented in non-selected rows by controlling the well region voltages of these rows. Sector erase operations are implemented by Fowler-Nordheim tunneling.

Abstract: A flash memory device is disclosed. The flash memory device includes a substrate, a memory cell transistor and a selection transistor. The substrate has a first region where the memory cell transistor is to be formed and a second region where the selection transistor is to be formed. The first region has an upper surface located within a first plane and the second region has an upper surface located within a second plane different from the first plane. The memory cell transistors may have a Fin-FET structure. The flash memory device may prevent a disturbance phenomenon in which an electron-hole pair infiltrates the memory cell transistor caused by a high integration degree of the flash memory device.

Abstract: A method of fabricating a memory cell including forming nanodots over a first dielectric layer and forming an intergate dielectric layer over the nanodots, where the intergate dielectric layer encases the nanodots. To form sidewalls of the memory cell, a portion of the intergate dielectric layer is removed with a dry etch, where the sidewalls include a location where a nanodot has been deposited. A spacing layer is formed over the sidewalls to cover the location where a nanodot has been deposited and the remaining portion of the intergate dielectric layer and the nanodots can be removed with an etch selective to the intergate dielectric layer.

Abstract: Methods and apparatuses are discussed which operate a nonvolatile memory cell or at least one cell in an array of such cells, such that a drain region or a source region is floating while adding charge to the charge storage structure.

Abstract: A non-volatile memory device includes a plurality of word lines, a plurality of sense lines, and a plurality of non-volatile memory cells. Each memory cell includes a floating gate transistor having a control gate, a floating gate separated dielectrically from the control gate, a drain connection and a source connection. The control gate is connected to one of the word lines and the source connection is connected to one of the sense lines, the drain connection being electrically isolated from the other memory cells. A method for reading the memory device and a method for operating the memory device are also provided.

Abstract: A NAND flash memory system with an array of individual charge storage elements, such as floating gates, arranged in a NAND string, each element being capable of selectively storing data in the form of charge there-in during a program or an erase operation, and during a read operation sensing the quantum of charge stored to provide reconstruction of data. Such a memory made with a floating gate that is spaced away from the diffusions and covered on all five sides except the channel side, by the control gate, there by having increased coupling with the associated advantage of lower high voltages, reduced impact of the unwanted disturb conditions, and providing for improved retention and reliability characteristics at higher operating temperatures is disclosed. The main emphasis in this technology is to provide a device with improved retention, endurance, and temperature characteristics meeting the Automotive specifications even with some area penalty.

Abstract: A process for reading data (including verifying during programming) from a selected non-volatile storage elements of a group (e.g., NAND string) of non-volatile storage elements includes maintaining an intermediate voltage as a control gate voltage for an unselected non-volatile storage element and subsequently changing the control gate voltage for the unselected non-volatile storage element from the intermediate voltage to a read enable voltage. The control gate voltage for the selected non-volatile storage element is raised from a standby voltage (which is different than the intermediate voltage) to a read compare voltage. While the control gate for the selected non-volatile storage element is at the read compare voltage and the control gate for the unselected non-volatile storage element is at the read enable voltage, the state of the selected non-volatile storage element is sensed to determine information about the data stored in the selected non-volatile storage element.

Abstract: A string of memory cells with a charge trapping structure is read, by selecting part of a memory cell selected by a word line. Part of the memory cell is selected by turning on one of the pass transistors on either side of the string of memory cells. The charge storage state of the selected part is determined by measuring current in a bit line tied to both pass transistors.

Abstract: A memory cell has a selection transistor constituted of an MOS transistor having a gate electrode and a cell transistor constituted of an MOS transistor having the same polarity as the selection transistor, in such a configuration that these two transistors are connected in series. A bit line is connected to a drain region of the selection transistor and a word line is connected to the gate electrode thereof. A gate electrode of the cell transistor is not electrically connected anywhere so as to be in a floating potential state, while a drain region thereof is connected to a source region of the selection transistor. A source line is connected to a source region of the cell transistor.

Abstract: A method of programming a silicon oxide nitride oxide semiconductor (SONOS) memory device is provided. The SONOS memory device includes a substrate, first and second impurity regions spaced apart on the substrate, a gate oxide layer formed over the substrate between the first and second impurity regions, a trap layer formed over the gate oxide layer, an insulation layer formed over the trap layer, and a gate electrode formed over the insulation layer. The method of programming the SONOS device includes writing data into the SONOS memory device by applying a first voltage to the first impurity region, a gate voltage to the gate electrode, and a second voltage to the second impurity region, where the second voltage is a negative voltage.

Abstract: An EPROM cell includes a semiconductor substrate, having source and drain regions, a floating gate, including a semiconductive polysilicon layer electrically interconnected with a first metal layer, and a control gate, including a second metal layer. The floating gate is disposed adjacent to the source and drain regions and separated from the semiconductor substrate by a first dielectric layer, and the second metal layer of the control gate is capacitively coupled to the first metal layer with a second dielectric layer therebetween.

Abstract: A memory cell with a charge trapping structure is read by measuring current between the substrate region of the memory cell and one of the source region of the memory cell and the drain region of the memory cell. The read operation decreases the coupling between different parts of the charge trapping structure when other parts of the charge trapping structure store data that are not of interest. The sensing window of the memory cell can be greatly improved by this read operation.

Abstract: A method for programming a non-volatile memory (NVM) cell includes applying an increasing voltage to the current electrode that is used as a source during a read. The initial programming source voltage results in a relatively small number of electrons being injected into the storage layer. Because of the relatively low initial voltage level, the vertical field across the gate dielectric is reduced. The subsequent elevation of the source voltage does not raise the vertical field significantly due to the electrons in the storage layer establishing a field that reduces the vertical field. With less damage to the gate dielectric during programming, the endurance of the NVM cell is improved.

Abstract: The capacitorless DRAM memory cell is constituted by a partially-depleted MOSFET device successively comprising a base substrate, a buried insulator, a floating substrate from semiconducting material including a channel, the gate insulator and a gate. The gate comprises a first zone doped by a first type of dopant and a second zone doped by a second type of dopant. The channel is doped by the second type of dopant. The gate insulator comprises a first part corresponding to the first doped zone and a second part corresponding to the second doped zone of the gate. The first part of the gate insulator has a higher tunnel resistance than the second part. Data storage is realized by means of charge carrier transportation from the gate to the floating substrate through the lower tunnel resistance part of the gate insulator.

Abstract: There is provided a technology capable of enhancing reliability in rewrite of storage information in a nonvolatile memory while checking an increase in area of a memory array thereof. With a memory array configuration, individual bit lines are connected to two memory cells sharing a source, and disposed at symmetrical positions, respectively, and two lengths of metal interconnections (the bit lines) are disposed with respect to a width in the direction of a channel width of a region occupied by one of the memory cells. In contrast, respective control gates of the memory cells corresponding to two word are rendered at an identical potential, and respective memory gates thereof are rendered at an identical potential, thereby disposing three lengths of metal interconnections (a control gate control line, memory gate control line, and common source line) with respect to a length of the regions occupied by the two memory cells in the direction of a channel length.

Abstract: A method of charging a floating gate in a nonvolatile memory cell comprises bringing a substrate channel within the memory cell to a first voltage, bringing a control gate to a programming voltage, and floating the substrate channel voltage while the control gate is at the programming voltage. Memory devices include state machines or controllers operable to perform the described method, and operation of such a state machine, memory device, and information handling system are described.

Abstract: A non-volatile memory device and drive method thereof uses a voltage bias condition to enable an electronic device to normally operate without employing a specific transistor, e.g., a recall transistor. The non-volatile memory device performs its function normally without the recall transistor, and by which a degree of cell integration can be considerably raised. A SRAM latch is controlled by the logic circuit, a SONOS (silicon-oxide-nitride-oxide-silicon) transistor is electrically connected to a Vcc node of the electronic device to store a high/low state of the SRAM latch according to a turn-on or turn-off state of power, and a pass transistor controls read, program, and erase operations of the SONOS transistor.

Abstract: An apparatus for controlling generation of pulses for refresh operations of a memory device having a pad to transfer information and to receive signals from an external interface. The apparatus includes a switch, coupled to a current source and to the pad receiving signals from the external interface. The switch outputs one of the signals from the current source or the pad in response to a switch control signal. An oscillator is coupled to the switch and generates the refresh operation pulses in response to the output from the switch.

Abstract: The semiconductor memory device includes an electrically erasable programmable non-volatile memory cell having a single layer of gate material and including a floating-gate transistor and a control gate. The source, drain and channel regions of the floating-gate transistor form the control gate. Moreover, the memory cell includes a dielectric zone lying between a first part of the layer of gate material and a first semiconductor active zone electrically isolated from a second active zone incorporating the control gate. This dielectric zone then forms a tunnel zone for transferring, during erasure of the cell, the charges stored in the floating gate to the first active zone.

Abstract: A memory cell with a charge trapping structure is operated by measuring current between the substrate region of the memory cell and at least one of the source region of the memory cell and the drain region of the memory cell. The read operation decreases the coupling between different parts of the charge trapping structure when other parts of the charge trapping structure store data that are not of interest. The sensing window of the memory cell can be greatly improved by this read operation. The memory cell is erased by increasing the net positive charge on the memory cell and programmed by increasing the net negative charge on the memory cell.

Abstract: A memory cell with a charge storage structure is read by measuring current between the substrate region of the memory cell and one of the current carrying nodes of the memory cell. The read operation decreases the coupling between different parts of the charge storage structure when other parts of the charge storage structure store data that are not of interest. The sensing window of the memory cell can be greatly improved by this read operation. Example arrangements are a series of memory cells, and an array of series of memory cells.

Abstract: A highly-reliable semiconductor device is realized. For example, each memory cell of a nonvolatile memory included in the semiconductor device is configured to include a source and a drain formed in a P-well, a memory node which is formed on the P-well between the source and the drain via a tunnel insulator and is insulated from its periphery, and a control gate formed on the memory node via an interlayer insulator. When a programming operation using channel hot electrons is to be performed in such a configuration, the P-well is put into an electrically floating state.

Abstract: Unit cells of a non-volatile memory device and a method thereof are provided. In an example, the unit cell may include a first memory transistor and a second memory transistor connected to each other in series and further connected in common to a word line, the first and second memory transistors including first and second storage nodes, respectively, the first and second storage nodes configured to execute concurrent memory operations. In another example, the unit cell may include a semiconductor substrate in which first and second bit line regions are defined.

Abstract: A method is described for erasing a selected data region in an NROM cell that is a member of a virtual ground NROM EEPROM array. The method provides that erasing the selected data region does not disturb the program state of unselected data regions.

Abstract: A memory cell with a charge storage structure is read by measuring current between the substrate region of the memory cell and one of the current carrying nodes of the memory cell. The read operation decreases the coupling between different parts of the charge storage structure when other parts of the charge storage structure store data that are not of interest. The sensing window of the memory cell can be greatly improved by this read operation. Example arrangements are a series of memory cells, and an array of series of memory cells.

Abstract: A flash memory cell includes a silicon substrate having a main surface, a source region in a portion of the silicon substrate proximate the main surface and a drain region in a portion of the silicon substrate proximate the main surface. The drain region is spaced apart from the source region. The memory cell includes a first dielectric layer formed on the main surface, a floating gate disposed above the first dielectric layer, an inter-gate dielectric layer disposed above the floating gate, a control gate disposed above the inter-gate dielectric layer, a second dielectric layer and a low-k dielectric spacer layer disposed on the second dielectric layer. The first dielectric layer covers a portion of the main surface between the source and the drain. The second dielectric layer surrounds outer portions of the first dielectric layer, the control gate, the inter-gate dielectric layer and the floating gate.

Abstract: A nonvolatile memory device comprises a memory cell array wherein a plurality of memory cell transistors are divided into multiple erase blocks. The multiple erase blocks are separated from each other by dummy word lines. During an erase operation of one of the multiple blocks, a dummy word line separating the one of the multiple blocks from other erase blocks is driven with a coupling inhibition voltage.

Abstract: Two-bit programmable nonvolatile memory devices and methods of operating and fabricating the same are provided. The device comprises a plurality of device isolation layers, a plurality of word lines crossing over the device isolation layers, and a multiple insulation layer intervened between the word line and the active region. The multiple insulation layer includes a charge trap insulation layer. A source/drain region is formed at each region defined by adjacent word lines and the adjacent device isolation layers. The source/drain regions have the same surface area. A write operation of the device comprises applying a first level voltage, a ground voltage, and a write voltage to one bit line, another bit line, and a selected word line, thereby writing data into a charge trap insulation layer. By changing the voltages applied to the bit lines, 2 bits may be stored in one memory cell.